Heat sealable stepped end bag



March 21, 1961 T. M. MCCURRY HEAT SEALABLE STEPPED END BAG Filed April50, 1959 llllllllllill\lllllnh. llllllllll 1.1.11....11'1'...lill-1.."

JNVENTOR. 7//0/7/95 M /Vc WH/PK HEAT SEALABLE STEPPED END BAG Thomas M.Mc'Curry, Savannah, Ga., assignor to Union Bag-Camp Paper Corporation,New York, N.Y., a corporation of Virginia nues Apr. so, 1959, ser. No.810,079

6 claims. (ci. 229-55) The present invention relates to improvements inbags. More particularly it pertains to a multiwall paper bag having aheat scalable inner ply.

At present hygroscopic, deliquescent, corrosive, semiliquid and otherhard-to-protect products are packaged and shipped in pails, drums andcans. Such containers are expensive, require large storage and shippingspace, and are more costly during shipping because of their weight andbulk. It is an object of the present invention to provide a bag whichovercomes such disadvantages but is just as efficient in use.

It is a further object of the invention to provide a at bag constructedin the form of a tube Vfrom two to six plies of paper and designed tohold up to 100 pounds of bulk product. The inner ply is coated with orformed of polyethylene or any other heat Sealable material. Furthermore,depending on the product being packaged, the plies can be made up ofvarious combinations of paper, paper and foil, or polyethylene coatedpaper and foil.

It is a further object of the invention to provide a heat sealable paperbag having the various plies stepped or offset so that the inner ply isexposed to take a direct heat seal application. Previously it wasimpractical to heat seal the inner ply of a multiwall bag because theseal had to be applied through `all the plies. These plies provided aninsulating barrier which prevented heat seal ing at acceptablecommercial speeds. In addition, the plies so dissipated the heat that itwas virtually impossible to form a clean, straight heat seal line. Withthe construction of the present invention it is possible to heat sealthe inner ply rapidly in a straight line. The entire lip can then befolded over and pasted to the youter face of the bag so that no pressureis exerted on the heat seal line.

It is another object of the invention to provide a bag which will form acompletely heat sealed, liquid and airtight package which eliminatesmoisture vapor transmission in either direction, which is simple indesign and rugged and strong in construction, and which is etlicient andeconomical for its intendeduse.

Other objects of the invention will in part be obvious and will in partappear hereinafter.,

The invention accordingly comprises an article of manufacture possessingthe features, properties, and the relation of elements which will beexemplified in the article hereinafter described and the scope of theinvention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing, in which:

Figure 1 is a plan View of the tube of the present invention with theinner ply opened up to show the longitudinal seam;

Figure 2 is a plan view of the flat tube of the present invention;

Figure 3 is a plan view ofthe tube of Figure 2 with the top and bottomlips folded and pasted to the outside of the bag;

Figure 4 is a plan view of the bag of Figure 3 with a strip of tapesecured over the closure at each end;

Figure 5 is an enlarged cross-sectional View on the line 5--5 of Figure1;

Figure 6 is an enlarged cross-sectional View showing the bottom closureof an opened bag;

Figure 7 is an enlarged cross-sectional View showing a filled bag on theline 7-7 of Figure 4.

Referring more particularly to the drawing, there is shown in Figures 1and 2 a tube 10 formed from four plies of paper with the outer pliesdesignated collectively Ias 11. Each of the outer plies, 11a, 11b and11e, has a longitudinal seam formed by adhesively securing together theoverlapped longitudinal edges. The inner ply 12 is of heat sealablematerial and can be made of various combinations. For example, ifpolyethylene is the heat scalable material, it can be an unsupportediilm, it can be laminated to a sheet of paper, or it can be a layer offoil laminated with polyethylene to a layer of paper with anothercoating of polyethylene over the foil. Although it is possible to form awaterproof longitudinal seam by overlapping the longitudinal edges ofthe inner ply and securing them together, it is much more effective andsafe to heat seal the two heat scalable faces of the inner ply in theform of a tin 13 and then turn such iin llat against the ply, as isshown in Figure 1. The Various plies are spot pasted to keep them inposition with respect to each other. f

It will be seen in Figures 1 and 2 `that the tube 10 has the pliesstepped or offset at each end so that the outer plies of one face of thebag extend beyond the inner ply which, in turn, extends beyond the outerplies of the other face of the bag. Although each end of the tube can bestepped toward the same face, it avoids waste during the manufacture ofthe tubes to have one end stepped toward one face with the other endstepped toward the other face, as is shown herein. By stepping the endof the bag Ias described, the inner ply 12 is exposed to take a directheat seal application. This permits heat sealing such ply much morerapidly than would be possible if the heat had to be applied through theouter plies. Furthermore, the rapid application of heat to the exposedply results in 'a clean, straight heat seal line 14 rather than a raggedheat seal over a large area with the faces of the ply joined togetherbelow the eventual fold line.

After the inner ply 12 has been heat sealed as described, adhesive 15 isapplied to the extended lip of the outer ply and the entire lip,consisting of such outer ply and the heat sealed inner ply, is foldedover along the top edge 16 of the short face and secured to such face.It will be apparent that any pressure will thus be exerted against thefold line rather than against the heat seal. A strip of tape 17 is thenadhesively secured yover the folded down lip and adjacent face and theends of the tape are turned over the side edges of the bag and securedto the opposite face, as shown in Figure 4. This insures a neat andtight closure. In some cases, where there are few plies or they are oflight weight, the pasted turned down; lip will provide a suflicient andeffective 4closure without the use of the tape.

Figures 6 and 7 show in cross-section the positions of the various pliesand tape in both the top and bottom closures. The bag manufacturer heatseals the bottom of the tube, pastes and folds over the lip of the outerply, and applies gummed tape over the folded lip. The bag user receivesthe bag in this condition, lls the bag with his product, then closes thetop of the bag with the same closure as is on the bottom. This resultsin a bag in which the factory closure and the customer closure are thesame thereby giving a neat, attractive package. One

method of forming the closures herein described is disclosed in thepending application of William C. Kerker, Serial No` 810,072, tiledApril 30, 1959.

Thus it will be apparent that the herein disclosed invention provides anew bag which is completely heat sealed, is` virtually airtight,eliminates moisture vapor transmission, costs less per unit than bre orsteel drums, pails or cans, is strong, requires a minimum of Warehousespace for empty or filled bags, is disposable and eliminates a returnprogram, has less tare Weight, and is vermin proof, grease proof, `acidresistant and not subject to oxidation.

Since certain changes may be made in the above article, and differentembodiments of the invention could be made without departing from thescope thereof, it is intended that all matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted asillustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. A heat sealable'stepped end bag comprising outer paper plies and aheat scalable inner ply formed into a tube, a closure at one end of thetube forming a bottom, the opposite end khaving the outer plies of oneface of the tube, the inner ply and the outer plies of the opposite faceeach extended beyond the other in stepped relationship with'tlie innerply exposed, said inner ply being heat seal-able adjacent the top edgeof said bag to close said tube. v

2. A heat scalable stepped end bag comprising an outer paper ply and aheat scalable inner ply formed into a tube, a closure at one end orf thetube forming a bottom, thel opposite end having the outer ply of `oneface of the tube, the inner ply and the outer ply of `the opposite faceeach extended beyond the other in stepped relationship, said inner plybeing heat sealed along a line adjacent the top edge to close the tube,said inner ply and extended outer ply being folded over along -a linebelow the heat seal line and secured to the opposite face.

3. The bag of claim 2 in which a tape is adhesively secured over theextended outer ply and the said opposite face.

4. A heat scalable stepped end bag comprising outer paper plies and aheat sealable inner ply formed into a tube, a bottom closure, the topend having the outer plies of one vface of the tube extended beyond theinner ply and the inner ply extended beyond the outer plies of theopposite face in stepped relation, -a heat seal band across the extendededge of the inner ply closing the tube, said inner ply and extendedouter ply being fold-ed over along a line below the heat seal band yandsecured to the opposite face.

5. The bag of claim 4 in which a tape is adhesively secured over theextended outer ply and the said opposite face.

6. A heat scalable stepped end bag comprising outer paper plies and aheat scalable inner ply formed into a tube, each end having the outerplies of one face of the tube extended beyond the inner ply and theinnerply being `extended beyond the outer plies of the opposite face instepped relation by providing longer outer plies than the heat-scalableinner ply extending beyond said inner ply at said one face and shorterouter plies than said inner ply at said opposite face, a heat seal bandacross the inner ply adjacent the end of the tube closing the tube, theinner ply and extended outer plies being folded over along a line belowthe heat seal band and secured to the opposite face.

References Cited in the tile of this patent UNITED STATES PATENTS2,015,199 Sparks Sept. 24, 1935 2,093,979 Farmer Sept. 21, 19372,114,623 Bergstein Apr. 19, 1938 2,298,421 Salsberg Oct. 13, 19422,387,812 Sonneborn Oct. 30, 1945

